#define _CRT_SECURE_NO_WARNINGS 1
#include <stdio.h>

int main() {
    double h1, h2, h3, h4, h5;
    scanf("%lf %lf %lf %lf %lf", &h1, &h2, &h3, &h4, &h5);
    double average = (h1 + h2 + h3 + h4 + h5) / 5;
    printf("%.2f", average);
    return 0;
}